Laparoscopic Sleeve Gastrectomy: Impact on Body Mass Index and Thyroid Hormones in Euthyroid Obese Patients.

BACKGROUND Obesity is still a major global public health problem and its incidence is increasing. Obesity leads to deterioration in thyroid functions. Even when they are within normal ranges, high normal levels of thyroid-stimulating hormone (TSH) increase morbidity and mortality. This study aimed to evaluate the body mass index (BMI) and TSH levels in 300 euthyroid patients with obesity before and after laparoscopic sleeve gastrectomy (LSG). MATERIAL AND METHODS A total of 300 euthyroid patients who underwent LSG between 2019 and 2021 were included in the study. Body mass index (BMI), thyroid-stimulating hormone (TSH), and free triiodothyronine (FT) 3 and tetraiodothyronine (FT4) levels were recorded before surgery and at 6 and 12 months after surgery and subsequently analyzed. RESULTS Mean BMI values were significantly lower at 6 and 12 months after surgery (P<0.001). There was a significant difference between mean TSH and FT4 levels before surgery and those at 6 and 12 months after surgery (P<0.001). However, mean FT3 levels remained unchanged 1 year after surgery (P=0.005). CONCLUSIONS LSG is not only effective in terms of weight loss, but also exhibits improving effects on thyroid hormone homeostasis in obese patients and provides protection against further adverse effects of TSH.

The relationship between abnormal urinalysis findings and appendicitis location.

AIMS: Acute appendicitis is a common cause of acute abdomen in general surgery and early diagnosis is crucial for prognosis. Abnormal urinalysis results have been associated with appendicitis in some studies, with reports of microscopic hematuria or pyuria in laboratory tests. The aim of this article is to evaluate the relationship between laboratory findings of hematuria, pyuria, and the location of acute appendicitis. METHODS: This retrospective study included 577 patients who underwent appendectomy for suspected acute appendicitis between January 1, 2018, and December 31, 2022, at the general surgery clinic of Samsun Training and Research Hospital. RESULTS: Among the 577 patients, 247 were female and 330 were male, with a median age of 34 years. A statistically significant difference was observed between appendicitis location and erythrocyte values (p = 0.009), specifically in paraileal and retrocecal locations. There was a statistically significant difference between appendicitis location and leukocyte values (p < 0.001), with significant differences found in paraileal, promontoric, and retrocecal locations. A statistically significant difference was observed between appendicitis location and leukocyte esterase values (p = 0.002), specifically in paraileal and retrocecal locations. DISCUSSION/CONCLUSION: Abnormal urinalysis findings are not uncommon in patients with acute appendicitis. Our study demonstrated a significant correlation between tit erythrocyte, tit leukocyte, and tit leukocyte esterase positivity with appendicitis locations. Therefore, we believe that pathological findings in urine tests of patients undergoing surgery with a preliminary diagnosis of appendicitis can provide valuable information to surgeons regarding the location of the appendix, ultimately aiding in optimizing the timing and cost of the operation.

Dynamic Digital Twin: Diagnosis, Treatment, Prediction, and Prevention of Disease During the Life Course.

A digital twin (DT), originally defined as a virtual representation of a physical asset, system, or process, is a new concept in health care. A DT in health care is not a single technology but a domain-adapted multimodal modeling approach incorporating the acquisition, management, analysis, prediction, and interpretation of data, aiming to improve medical decision-making. However, there are many challenges and barriers that must be overcome before a DT can be used in health care. In this viewpoint paper, we build on the current literature, address these challenges, and describe a dynamic DT in health care for optimizing individual patient health care journeys, specifically for women at risk for cardiovascular complications in the preconception and pregnancy periods and across the life course. We describe how we can commit multiple domains to developing this DT. With our cross-domain definition of the DT, we aim to define future goals, trade-offs, and methods that will guide the development of the dynamic DT and implementation strategies in health care.

An intraoperative serum parathormone level study in patients with chronic renal failure that underwent subtotal parathyroidectomy What extent of decrease is sufficient at which moment?

AIM: The aim of this study is to determine when to perform intraoperative parathormone (ioPTH) measurement and what extent of decrease in intraoperative serum PTH concentrations indicate success in the operations performed on patients with SHPT associated with chronic renal failure. MATERIAL AND METHODS: 50 consecutive patients who underwent subtotal parathyroidectomy between January 2012 and January 2019 were retrospectively included in this study. Patients were grouped according to persistent hyper parathyroidism (Group1, n:6) and curative surgery (Group 2, n:44). Preoperative serum PTH, calcium, phosphorus and ALP concentrations, intraoperative serum PTH concentrations; and serum PTH, calcium, phosphorus and ALP concentrations of 24th hour after surgery were included to the study. Intraoperatively, 20 minutes after parathyroid gland removal, blood was drawn for PTH assay. The changes in PTH levels between preoperative and intraoperative serum samples were calculated in percentage (ioPTH%) and postoperative 6th month serum PTH and ALP concentrations were included in the study. RESULTS: No significant differences were found by gender, BMI, elapsed period of dialysis treatment and preoperative laboratory values between Group 1 and Group 2. The meanage of Group 1 was 35 years which is lower than Group 2. With the second group, the mean decrease in PTH levels between intraoperative and preoperative serum samples (ioPTH%) was about 90%, which was higher than Group 1. CONCLUSIONS: In conclusion, we believe that, to encounter fewer persistent SHPT cases, it is essential that surgeons monitor ioPTH concentration 20 minutes after gland removal and confirm a decrease of 90% or more in ioPTH concentration. And we should not forget that young patients may tend to develop persistent SHPT. KEY WORDS: Chronic renal failure, Intraoperative parathormone, Secondary hyperparathyroidism, Parathyroidectomy, Subtotal patathyroidectomy.

Temperature-based MRI safety simulations with a limited number of tissues.

PURPOSE: Demonstrate ability to produce reasonable simulations of temperature using numerical models of the human body with a limited number of tissues. METHODS: For both a male and female human body model, numerical simulations were used to calculate temperature distributions in three different models of the same human body: the original model with 35 tissues for the male model and 76 tissues for the female model, a simplified model having only three tissues (muscle, fat, and lung), and a simplified model having six tissues (muscle, fat, lung, bone, brain, and skin). RESULTS: Although a three-tissue model gave reasonable specific absorption rate estimates in comparison to an original with many more tissues, because of tissue-specific thermal and physiological properties that do not affect specific absorption rate, such as rate of perfusion by blood, the three-tissue model did not provide temperature distributions similar to those of the original model. Inclusion of a few additional tissues, as in the six-tissue model, produced results in much better agreement with those from the original model. CONCLUSION: Reasonable estimates of temperature can be simulated with a limited number of tissues, although this number is higher than the number of tissues required to produce reasonable simulations of specific absorption rate. For exposures primarily in the head and thorax, six tissues may be adequate for reasonable estimates of temperature.

Comparision of Hem-o-lok polymeric clip and tri-staple in laparoscopic splenectomy.

AIM: This study aimed to compare the hem-o-lok polymeric clip (HC) and tri-staple (TS) methods used in dividing the splenic hilum in terms of results, and to reveal their superiority to each other. MATERIAL AND METHODS: Medical records of patients undergoing elective laparoscopic splenectomy at the Ondokuz Mayis University Faculty of Medicine General Surgery Clinic between March 2011 and March 2020 were retrospectively analyzed. Forty-two laparoscopic splenectomy cases performed using hem-o-lok polymeric clip (HC) or tri-staple (TS) were included in this study. Demographic features, primary diagnoses, splenic size, intraoperative data and postoperative complications, as well as the clip and stapler prices used in the surgery were analyzed. RESULTS: The mean operative time was significantly longer for HC group than TS group (116.7 min vs. 87.6 min, p<0.05). The mean cost of surgical instruments used to divide the splenic hilum was significantly lower for HC group than TS group (34.1 usd vs. 165.4 usd, p<0.05). There was no postoperative mortality, with a morbidity rate 6 (26.1%) for TS group and 4 (21.1%) for HC group (p>0.05). No significant difference existed in the complication rates. CONCLUSIONS: In the HC group, the operation time was longer, but the surgical cost was significantly lower. There was no significant difference when comparing other perioperative results. Although both techniques can be applied safely, we would like to emphasize that hemostasis is the most important factor for good results. KEY WORDS: Hem-o-lok polymeric clip, Laparoscopic splenectomy, Tri-staple.

Parallel transmit pulse design for patients with deep brain stimulation implants.

PURPOSE: Specific absorption rate (SAR) amplification around active implantable medical devices during diagnostic MRI procedures poses a potential risk for patient safety. In this study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients with deep brain stimulation (DBS) implants. METHODS: We performed electromagnetic simulations at 3T using a uniform phantom and a multitissue realistic head model with a generic DBS implant. Our strategy is based on using implant-friendly modes, which are defined as the modes of an array that reduce the local SAR around the DBS lead tip. These modes are used in a spokes pulse design algorithm in order to produce highly uniform magnitude least-squares flip angle excitations. RESULTS: Local SAR (1 g) at the lead tip is reduced below 0.1 W/kg compared with 31.2 W/kg, which is obtained by a simple quadrature birdcage excitation without any sort of SAR mitigation. For the multitissue realistic head model, peak 10 g local SAR and global SAR are obtained as 4.52 W/kg and 0.48 W/kg, respectively. A uniform axial flip angle is also obtained (NRMSE <3%). CONCLUSION: Parallel transmit arrays can be used to generate implant-friendly modes and to reduce SAR around DBS implants while constraining peak local SAR and global SAR and maximizing flip angle homogeneity.

Stepped impedance resonators for high-field magnetic resonance imaging.

Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high-field magnetic resonance imaging. In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections, referred to as stepped impedance resonators (SIRs), is investigated. Single-element simulation results in free space and in a phantom at 7 T (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 T in a phantom and human head illustrate the improvements in a transmit magnetic field, as well as RF efficiency (transmit magnetic field versus specific absorption rate) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements.

Dynamically applied B1+ shimming solutions for non-contrast enhanced renal angiography at 7.0 Tesla.

The purpose of this study was to detail a strategy for performing non-contrast enhanced renal magnetic resonance angiography studies at 7.0 T. It is demonstrated that with proper B1+ management, these studies can be successfully performed at ultrahigh field within local specific absorption rate constraints. An inversion prepared gradient echo acquisition, standard for non-contrast renal magnetic resonance angiography studies, required radiofrequency pulse specific B 1+ shimming solutions to be dynamically applied to address the field dependent increases in both B(0) and B1+ inhomogeneity as well as to accommodate limitation in available power. By using more efficient B1+ shimming solutions for the inversion preparation and more homogeneous solutions for the excitation, high quality images of the renal arteries were obtained without venous and background signal artifacts while working within hardware and safety constraints. Finite difference time domain simulations confirmed in vivo measurements with respect to B1+ distributions and homogeneity for the range of shimming strategies used and allowed the calculation of peak local specific absorption rate values normalized by input power and B1+. Increasing B1+ homogeneity was accompanied by decreasing local specific absorption rate per Watt and increasing maximum local specific absorption rate per [B1+](2), which must be considered, along with body size and respiratory rate, when finalizing acquisition parameters for a given individual.

Performance of external and internal coil configurations for prostate investigations at 7 T.

Three different coil configurations were evaluated through simulation and experimentally to determine safe operating limits and evaluate subject size-dependent performance for prostate imaging at 7 T. The coils included a transceiver endorectal coil (trERC), a 16-channel transceiver external surface array (trESA) and a trESA combined with a receive-only ERC (trESA+roERC). Although the transmit B(1) (B 1+) homogeneity was far superior for the trESA, the maximum achievable B 1+ is subject size dependent and limited by transmit chain losses and amplifier performance. For the trERC, limitations in transmit homogeneity greatly compromised image quality and limited coverage of the prostate. Despite these challenges, the high peak B 1+ close to the trERC and subject size-independent performance provides potential advantages especially for spectroscopic localization where high-bandwidth radiofrequency pulses are required. On the receive side, the combined trESA+roERC provided the highest signal-to-noise ratio and improved homogeneity over the trERC resulting in better visualization of the prostate and surrounding anatomy. In addition, the parallel imaging performance of the trESA+roERC holds strong promise for diffusion-weighted imaging and dynamic contrast-enhanced MRI.

Adapted RF pulse design for SAR reduction in parallel excitation with experimental verification at 9.4T.

Parallel excitation holds strong promises to mitigate the impact of large transmit B(1) (B(1)(+)) distortion at very high magnetic field. Accelerated RF pulses, however, inherently tend to require larger values in RF peak power which may result in substantial increase in Specific Absorption Rate (SAR) in tissues, which is a constant concern for patient safety at very high field. In this study, we demonstrate adapted rate RF pulse design allowing for SAR reduction while preserving excitation target accuracy. Compared with other proposed implementations of adapted rate RF pulses, our approach is compatible with any k-space trajectories, does not require an analytical expression of the gradient waveform and can be used for large flip angle excitation. We demonstrate our method with numerical simulations based on electromagnetic modeling and we include an experimental verification of transmit pattern accuracy on an 8 transmit channel 9.4T system.

Adapted RF pulse design for SAR reduction in parallel excitation with experimental verification at 9.4 T.

Parallel excitation holds strong promises to mitigate the impact of large transmit B1 (B+1) distortion at very high magnetic field. Accelerated RF pulses, however, inherently tend to require larger values in RF peak power which may result in substantial increase in Specific Absorption Rate (SAR) in tissues, which is a constant concern for patient safety at very high field. In this study, we demonstrate adapted rate RF pulse design allowing for SAR reduction while preserving excitation target accuracy. Compared with other proposed implementations of adapted rate RF pulses, our approach is compatible with any k-space trajectories, does not require an analytical expression of the gradient waveform and can be used for large flip angle excitation. We demonstrate our method with numerical simulations based on electromagnetic modeling and we include an experimental verification of transmit pattern accuracy on an 8 transmit channel 9.4 T system.

A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 Tesla.

A novel geometrically adjustable transceiver array system is presented. A key feature of the geometrically adjustable array was the introduction of decoupling capacitors that allow for automatic change in capacitance dependent on neighboring resonant element distance. The 16-element head array version of such an adjustable coil based on transmission line technology was compared to fixed geometry transmission line arrays (TLAs) of various sizes at 7T. The focus of this comparison was on parallel imaging performance, RF transmit efficiency, and signal-to-noise ratio (SNR). Significant gains in parallel imaging performance and SNR were observed for the new coil and attributed to its adjustability and to the design of the individual elements with a three-sided ground plane.

Local B1+ shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements.

High-quality prostate images were obtained with transceiver arrays at 7T after performing subject-dependent local transmit B(1) (B(1) (+)) shimming to minimize B(1) (+) losses resulting from destructive interferences. B(1) (+) shimming was performed by altering the input phase of individual RF channels based on relative B(1) (+) phase maps rapidly obtained in vivo for each channel of an eight-element stripline coil. The relative transmit phases needed to maximize B(1) (+) coherence within a limited region around the prostate greatly differed from those dictated by coil geometry and were highly subject-dependent. A set of transmit phases determined by B(1) (+) shimming provided a gain in transmit efficiency of 4.2 +/- 2.7 in the prostate when compared to the standard transmit phases determined by coil geometry. This increased efficiency resulted in large reductions in required RF power for a given flip angle in the prostate which, when accounted for in modeling studies, resulted in significant reductions of local specific absorption rates. Additionally, B(1) (+) shimming decreased B(1) (+) nonuniformity within the prostate from (24 +/- 9%) to (5 +/- 4%). This study demonstrates the tremendous impact of fast local B(1) (+) phase shimming on ultrahigh magnetic field body imaging.

9.4T human MRI: preliminary results.

This work reports the preliminary results of the first human images at the new high-field benchmark of 9.4T. A 65-cm-diameter bore magnet was used together with an asymmetric 40-cm-diameter head gradient and shim set. A multichannel transmission line (transverse electromagnetic (TEM)) head coil was driven by a programmable parallel transceiver to control the relative phase and magnitude of each channel independently. These new RF field control methods facilitated compensation for RF artifacts attributed to destructive interference patterns, in order to achieve homogeneous 9.4T head images or localize anatomic targets. Prior to FDA investigational device exemptions (IDEs) and internal review board (IRB)-approved human studies, preliminary RF safety studies were performed on porcine models. These data are reported together with exit interview results from the first 44 human volunteers. Although several points for improvement are discussed, the preliminary results demonstrate the feasibility of safe and successful human imaging at 9.4T.

B(1) destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil.

RF behavior in the human head becomes complex at ultrahigh magnetic fields. A bright center and a weak periphery are observed in images obtained with volume coils, while surface coils provide strong signal in the periphery. Intensity patterns reported with volume coils are often loosely referred to as "dielectric resonances," while modeling studies ascribe them to superposition of traveling waves greatly dampened in lossy brain tissues, raising questions regarding the usage of this term. Here we address this question experimentally, taking full advantage of a transceiver coil array that was used in volume transmit mode, multiple receiver mode, or single transmit surface coil mode. We demonstrate with an appropriately conductive sphere phantom that destructive interferences are responsible for a weak B(1) in the periphery, without a significant standing wave pattern. The relative spatial phase of receive and transmit B(1) proved remarkably similar for the different coil elements, although with opposite rotational direction. Additional simulation data closely matched our phantom results. In the human brain the phase patterns were more complex but still exhibited similarities between coil elements. Our results suggest that measuring spatial B(1) phase could help, within an MR session, to perform RF shimming in order to obtain more homogeneous B(1) in user-defined areas of the brain.